I need to retrieve surface values of a parameter in high mountainous region that are in hybrid sigma coordinate system.
From what I have understood, hybrid sigma coordinate has three layers in the bottom there is pure sigma region which is able to capture the signature of the mountains at the very top of the atmosphere, pure hybrid sigma coordinate in the middle and Pure pressure region at the top.
So since the pure sigma region captures the signature of the mountain, does that mean the lower level values, in this figure (K+1/2) equals to surface values?